Grid lining fob centrifugal



.June 29, 1937. ROBERTS GRI-D LINING FOR ,CENTRIFUGAL BASKETS Original Filed April 14,: 1934 Reissued June 29, 1 937 Rs. 20,432 a UNITED STATES PATENT OFFICE cam LINING non onu'rnmuon. nssnn'rs Eugene Roberts, H's-stings, N. Y., asaignor to The Western States Machine Company, Salt City, Utah, a corporation of Utah Original No.

Serial No. 720,614, April 14,, 1934.

2,028,168, dated January 21, 1938,

Application '.for reissue December 16, 1936, No.

'tion for centrifugal baskets and is intended to provide a construction of grid lining or backing v element for supporting the fine filter element or sieve in order to facilitate the eflicien't drainage of the liquid that has passed through the filtering sieve on its way to the outlet holes in the basket wall. The efliciency of liquid extraction in a centrifugal basket depends in part upon providing a spacing element or support for holding the fine fllter sieve in spaced relation away from the basket wall, while aflording conduits or passages for the rapid unimpeded flow of the liquid in the outlet holes in the basket walL If the how of liquid from the sieve to the outlet holes be expedited through provision of suitable and ample drainage es aiforded by the backing or spacing element, the tendency of the liquid. to cause gumming up and obstruction. of these passagesis largely eliminated and the centrifugal will continue to operate at full eihciency.

In my former Patent No. 1,581,989 granted April 13, 1926, I showed a grid lining or backing containingopeningsof large area surrounding each outlet hole of the basket and. while this arrangement was superior to the prior art constructions, I have discovered that it is possible to obtains. substantially higher degree of eihciency if the drainage areas, affording communiopeningsin the structiouthat will provide ample circumferential es for the circumferential flow of the liqelement ofsuch strength'and stiffness andstill of cation between the filter sieve and the outlet basket, are arranged to extend circmnferentially of liquid, that passes throughthe sieve, to have relative movement in a direction reverse to the rotati'on of the basket without obstruction and the. present invention is intended to provide a conthe outlet holes without impediment, while atthesametimeprovidingaspacing gridor light weight that will withstand the very heavy outward pressure of the centrifuged-material without collapsing or bending.

The present invention embodies the principles which I have discovered by providing a rigid grid,

preferably of sheet metal, capable'of withstanding a much higher pressure than is needed for centrifugal requirements without collapsing. and at the same time providing circumferential pasliquor is thebasketsoastoallowthesages at the back of the sheet that are amply large to provide complete and unobstructed drainage to all the outlet holes formed in the centrifugal basket wall.

The provision of unobstructed circumferential 5 passages between the supporting grid and the basket wall is particularly important in the centrifugal separation of material such assugar from the viscous liquors surrounding the sugar crystals.

'These passages permit the liquor to be flashed m from the crystals during acceleration of the hasket to full speed and to lag'behind the movement of the basket itself while seeking an outlet through the basket wall. Without them, the

obstructed in its tendency to flow cir- 15 cumferentially, and when a large amoimt of liquor is quickly removed from the sugar it backs up'into the sugar wall, causing gumming or smear and imperfect filtration.

Another important advantage of the improved 20 construction is that it supports filter lining elements uniformly throughout the area of the linlugs and at-a uniform distance from the basket wall, thus preventing irregularities from developinginthe lininssduetohigh centrifugalpres- 25 sures and ensuring optimum filtration.

A preferred embodiment of my improved spacing grid comprises a metallic sheet formed. with spaced rows of perforations and intervening rows of depressed, dome-like bosses projecting 39 from the back of the sheet to form a multiplicity ofiirm supportsspacingthesheetfromthebasket wall and providing wholly unobstructed passages for the flow of liquid to the outlet holes of the basket. This and ctherfeatures of the 5 invention will be described in the following speciflcationand will be defined in the claims hereto In the drawing 1 have shown one form that illustrates and embodies the principle ofthis invention, in which.

Fig.1 isaviewshowingtheinsldeorfrontface. of the sheet. i

Fig.2isaviewshpwingthebackorrearface of the sheet.

' Fig.3 isacrosssectional'view ontheplaneindicated by line of Fig. 2. Y

Fig. 4 is a vertical radial section through the periphery of a basket showing in complete filter lining assemblage in transverse section on a u slightly enlarged scale, the middle portion of the basket and lining being broken away to permit illustration on a sufficiently large scale for better illustration. The filter thickness is exaggerated.

Fig. 5 is a horizontal section showing the overlapped end portions of the grid in a centrifugal basket.

Fig. 6 is an elevation showing the fiat overlapping portion of one end of the grid.

According to the practice illustrated in the accompanying drawing, I provide a thin flat sheet of metal I and punch out spaced rows of perforations, as shown at 2, and preferably the punch-receiving opening in the die is countersunk so that when the hole is punchedout the.

edge of the opening is offset or depressed to form an annular stiffening or reenforcing lip 2a surrounding the opening.

Portions of the area. between two adjacent rows of perforations 2 are also pressed rearwardly to form concavo-convex bosses 3 of a dome-like shape and the apical portions of these oflset dome-like bosses are formed with short radial slits or notches extending from the bottom or center of the boss toward the base portion thereof, as illustrated at 30, forming three short spaced tips which contact with the smooth face of the basket wall.

' It will be seen that every perforation of the metal is surrounded with a rearwardly offset continuous rim or lip, as at 2a and as at 3, in

' the latter case the reenforcing ring being formed by depressing the material to form a substantially projecting deep boss, in this case terminating in a three-point contact and provided with openings to prevent accumulation of the liquid in the front or hollow face of the boss. A light thin sheet with this construction can be made exceedingly stiff and firm, while all the ridges surrounding and separating the depressions and perforations are'formed with a very smooth, partly rounded surface presenting a most satisfactory surface for the support of the other elements of the filter lining.

In Fig. 4 I have illustrated the preferred assemblage of a complete lining in a perforated centrifugal basket comprising the peripheral cylindrical wall In surrounded with usual reenforcing bands or rings II and having top and bot-- tom members II and II of usual or desired construction.

In this assemblage the pressed metal grid I is inserted inside the basket and fits snugly against the perforated wall III of the basket and, by reason of the support of its multiple spacing bosses 3, provides very substantial circumferential drainage channels affording no obstruction or impedance to the circumferential flow of the liquid into the outlet holes Illa that have communication with the circumferential passages between the bosses.

In the assemblage shown, I have placed against the inside face of the grid lining a wire mesh lining member I, about No. 8 mesh, whose top and bottom edges are embedded in selvage strips or borders of packing .material somewhat similar to that disclosed in my United States Patent No. 1,946,500, dated February 16, 1934. The filter sieve element li'is then placed inside the wire mesh intermediate lining and, in this case, is

shown as comprising a composite filter element embracing avery finely perforated thin sheet lib and a coarsely perforated heavier backing sheet lia integrally united to form a single element which, however, forms no part of the present invention as it is the subject of another copending application filed by me.

Obviously the principal drainage of the liquid that has passed through the filtering sieve elementwill be effected through the holes 20, which open into circumferential passages leading directly to the outlet holes in the basket wall. The slitting of the bosses allows a portion of the liquid to escape to the outlet holes, either directly or 10 through the circumferential passages. With this arrangement, complete freedom is given for the liquid laggingbehind the high speed revolution of the basket, while the individual channels have free communication with each other laterally between the supporting bosses.

To permit proper overlapping of the ends of the grid when placed in the basket, the end portion la of the sheet I is provided with simple perforations 5 and left flat without any upset bosses 3 or stiffening flanges 2a. Preferably the fiat overlapping area I a at one end of the. sheet is ground off or beveled to a feather edge to avoid leaving any shoulder that would tend to form a vertical crease or shoulder in the delicate filter lining element that is supported by the grid. This permits stretch or circumferential play between the two overlapped ends of the grid and the flat overlap la should point in the direction opposite to the rotation of the basket to avoid any possibility of catching against the usual plow tip, which also extends in a directlonopposite to the revolution of the basket.

While the sheet metal grid may be made of any suitable material, it is preferred for most purposes to make this grid of a non-corrosive sheet metal such as, for example, Monel metal.

In practice the metallic sheet, before being punched, may have one end perforated as at la in Fig. 6 before being fed through the perforating 40 and upsetting machine. Then the remainder of the sheet will be subjected to the action of the perforating and upsetting punches to form the offset domes and intermediate perforations which characterize the main body of the grid. The 4 length of the sheet will be somewhat greater than the inside circumferential measure of the basket for which it is intended, so that there will be a sufllcient gap between the opposing tiers of bosses on the opposite end portions of the grid to take upthe stretch-as the grid becomes adjusted to the interior wall of the basket by the outward 1 pressure of the centrifuged material.

In the foregoing description I have set forth details of construction of a preferred embodiment of the invention, but without intention that the invention be restricted to such details, except as required by the claims. It extends to grids or backings made of rigid material-capable of withstanding higher pressures than are 50 encountered in centrifugal operations without ""collapsing andto the provision therewith of ample facilities for flow of the centrifugally separated liquid through. the backing and for drainage of this liquid to outlet openings of the basket wall by way of unobstructed circumferential passages.

I claim:

1. A filter supporting and spacing grid for a centrifugal basket lining comprising a metallic 7 sheet formed with spaced. rows of perforations, and intervening rows of spaced depressed domelike hollow bosses projecting from the back of the sheet to form a multiplicity of fi m supp rts spacing thesheet from the basket. wall and pro- 7 uid in a circumferential direction to the outlet holes in the basket wall.

2; A filter supporting and spacing grid for a centrifugal basket comprising a pressed metal sheet formed with spaced rows of perforations whose edges are offset to-provide reenforcement for that portion of the metal, andintervening rows of depressed dome-like bosses projecting frmn the back of the sheet to form a multiplicity of firm supports spacing the sheet from the basket wall. V

3. A filter supporting and spacing grid for a centrifugal'basket comprising a metallic sheet formed with spaced rows of perforations, and intervening rows of depressed dome-like bow projecting from the back of the sheet to form a multiplicity of firm supports spacing the sheet from the basket wall, said bosses having their apical portions slitted to subdivide the apical portions into spaced prongs and afford drainage for the interior of said-dunes.

4. A' filter supporting and spacinggrld fora centrifugal basket comprising a metallic sheet formed with spaced rows of perforations whose edges are offset toform peripheral stiffening lips, and intervening rows of depressed concavoconvex bosses projecting a substantial distance from the baekofthesheetto formamultiplicity offirmrearwardlyoifsetsupportstospacethe sheetfrom the basketwall,saldbosseshaving their bottom portion provided with slits forming atriangularopeninginthebottomportion of 5.A filtersheetsupportingandspacmggrid foracentrlfugalbasketcmnprlsingametallic sheet formed with spaced rows of. relatively coarseascomparedwiththeopeningsinitsfiltersheehandinterveningrowsd dome-like hollow bosses mole l fromthebackoftliesheettoformamultiplicity" of firm supports to space the-sheet from the basket in relation to the aforesaid perfora- 6.Afilterandspadn88 dfora .centrmmal basket a-perforated me- 'tallicsheetprovidedwithrearwardlyofisetspac- ,againstthefront-faceof encountered in centrifuging sheethetweenrorws ingbosses extending in rows lengthwise of the of perforations. one end of said sheet having a list transverse margin l perforated area mitthe fiat'area of the sheet to lie smooth the other end in overlapped relation.

'1. A filter supporting and spacing grid for a centrifugal basket comprising a perforated metallic sheet provided with rearwardly offset spacingbossesextendinginrowslengthwisc ofthe sheet-between rows of perforations, one end of said sheet having a fiat transverse marginal perforated area without projecting bosses to permit the fiat'area of the sheet to lie smooth again the front face of the other end in overlapped relation, being reduced to a feather edge.

8. In combination, a con basket for separating crystals from liquid, and like uses, comprising a vertical wall having outlet perforations for the w of liquid therethrough, It s dbacklns-of etalreslstant to adjacent the inside ofsaid wall and providing a'base for a filter lining, said backing having op nin s therein of relatively large dimensions in comparison with viding unobstructed es for the flow of liq V withmt proiectlng bossesto pere the fiat end portion of said sheet the openings in the filtering means which it is adapted to support whereby to enable free passage of liquid ;to said wall, a plurality of circumferentially extending supporting means spaced apart vertically betweenthe backing and wall in a manner to support the backing away from the wall and to provide circumferential channels between the backing and wall for unimpeded circumferential fiow of liquid adjacent the inside of the wall during a centrifuging operation, and filtering means lyi adjacent the inside of said linin 9. A rigid backing for supporting and spacing a filter lining ina centrifugal basket, and composed of material resistant to pressures encoun- I tered in centrifuging, comprising a metallic sheet presenting a face for supporting filtering means,

said sheet having a multiplicity of openings therein of relatively large dimensions in comparison with the openings in the filtering means which the backing is adapted to support whereby to enable free drainage of liquid from the filtering means to the basket wall and a plurality of circumferentially extending supporting means spaced apart vertically whereby to support the backing away from the wall and to provide cir- Y cumferentially extending channels between the backing and wall for unimpeded circumferential flow of liquid adjacent the inside of the wall during a centrifuging operation. v

10. A rigid backing for n andspacing a filter lining -in a centrifugal basket, and composed ofmaterial resistant to pressures encoun texed'in centrifugim, comprising a metallic sheet presenting a face for supporting filtering means,

said sheet having a multiplicity of openings.

therein of relatively large dimensions in comparisonwiththeopeningsinthe filteringmeans -whichthebackingisadaptedtosupportwhereby toenablefreedrainageofliquidfromthefilteringmeanstothebasketwallandaplurality of circumferentially extending supporting means spacedapar'tverticallywherebytosupportthe backlngaway fromthewalland toproyide circumferentiallyextending channels between the backlngandwsllforunimpeded circumferential ficwofliquidadlacenttheinsideofthewail during acentrifuging operation. each of said 11. A rigid backing for supporting and spacing afilterlining inacentrifugalbasket, an'dcomposed of material resistant to pressures encoime tered in centrifuging, comprising a metallic sheet circmnferentially extendtng means lncludingaseriesof projectionssecuredtothe' presenting a face for supporting filtering means.

said sheet having a multiplicity of openings therein of relatively large dimensions in comparlsonwiththeopeningsinthefiiteringmeans' which the backing is adapted to support whereby toenable free drainage of liquid from the filtering means to the basket wall and a plurality of circumferentially extending supporting means spaced apart vertically whereby to support the backing away from the wall and to provide cir cumferentially extending channels'between the backing and wall for unimpeded circumferential how of liquid adjacent the inside ofrthe wall during a centrifuging operation, each of said circumferential y extending supporting means including a series of projections pressed from said sheet. and adapted to engage the wall.

12. A rigid backing for supporting and spacing a filter lining in a centrifugal basket, and

composed of material resistant to p en-.-

of the wall during a centrifuging operation, each of said circumferentially extending supporting means including a series of projections pressed from said backing and adapted to engage the wall, the depressed projections being provided 5 with openings to permit the flow of liquid therethrough and laterally therefrom.

EUGENE ROBERTS. 

